Method of and apparatus for making flat metal tubes



June 8, 1948. L. G: GLESMANN 2,442,850

METHOD OF AND APPARATUS FOR MAKING FLAT METAL TUBES Filed Dec. 20, 19433 Sheets-Sheet l Invenifow L 6.616 M m v June 8, 1948. 1.. G. GLESMANN2,442,850

METHOD OF AND APPARATUS FOR MAKING FLAT METAL TUBES Filed. Dec. 20, 19433 Sheets-Sheet 2 .1; 11267111 12121 WWO R mwrmm bk .lIl'lIl-ll v m. mw

in ir June 8, 1948. 2,442,850

METHOD OF AND APPARATUS FOR MAKING FLAT METAL TUBES L. G. GLESMANN 5SheetsSheet 3 Filed Dec. 20, 1943 Patented June 8, 1948 METHOD OF ANDAPPARATUS FOR MAKING FLAT METAL TUBES Louis G. Glesmann, Rome, N. Y.,assignor to Revere Copper and Brass Incorporated, Rome, N. Y., acorporation of Maryland Application December 20, 1943, Serial No.515,034

11 Claims. 1

My invention relates to apparatus for and methods of making flat metaltubes.

The invention, which has among its objects a method of making such tubesparticularly adapted to be practised by rolling operations, will be bestunderstood from the following description when read in the light of theaccompanying drawings of examples of the method and apparatus forperforming it, while the scope of the invention will be moreparticularly pointed out in the appended claims.

In the drawings:

Fig. 1 is a plan of the right hand portion of apparatus according to theinvention with parts broken away;

Fig. 2 is an elevation of the portion of the apparatus according to Fig.1;

Fig. 3 is a plan of the left hand portion of apparatus according to theinvention with parts broken away, being a continuation of the apparatuspartly shown by Fig. 1, the fragments of the gear and grooved roll shownat the extreme right of Fig. 3 being part of the same gear and groovedroll shown at the extreme left of Fig. 1;

Fig. 4 is an elevation of the apparatus according to Fig. 3 with partsbroken away;

Fig. 5 is a section on the line 5--5 of Fig. 4 on an enlarged scale withparts in elevation;

Figs. 6, '7 and 8 are, respectively, sections on the lines 66, 1'! and8-8 of Fig. 3 on an enlarged scale;

Fig. 9 is a section on the line 9-9 of Fig. 4 on an enlarged scale withparts omitted;

Fig. 10 is an elevation according to Fig. 9;

Fig. 11 is a schematic diagram of the gearing according to Figs. 1 to 4;

Figs. 12 to 16 are, respectively, sections on the lines l2-l2 to iii-l6inclusive of Fig. 2 on an enlarged scale;

Figs. 17 to 22 are, respectively, sections on the lines l'l-l l to 22-22inclusive of Fig. 4 on an enlarged scale; and

Fig. 23 is a section corresponding to Fig. 21 showing a tube of modifiedcross-section.

Heretofore seamless tubes of flattened crosssection have been formedfrom tubes of circular cross-section by use of a plug die, that is tosay, by drawing the tube of circular cross-section through a die openingand over a plug positioned in that opening, the die opening and plughaving respectively the cross-sectional shapes of the exterior andinterior surfaces of the flattened tube. Commonly it is necessary toperform the drawing operation in two steps, the first consisting of arough drawing operation and the second a finished drawing operation.Likewise it is necessary when drawing the tubes to preliminarilystraighten the tube of circular cross-section before it is drawn so asto secure a straight flat tube, it being impossible for such tubes whenthey are of rather small cross-section and of thin gauge to bestraightened on account of the straightening operation buckling the tubeWalls. Still further, because of the necessity of supporting the plugemployed in the drawing operation on a rod which projects beyond the endof the seamless tube being operated on the length of flat tube that canbe formed is rather limited.

According to the present invention, flattened seamless tubes are formedby a rolling operation preferably starting with the tube of circularcross- 7 section, the invention being particularly applicable to tubesof relatively small size and thin gauge. For example, but withoutlimitation thereto, a copper tube of circular cross-section having anoutside diameter of 0.5 inch with a wall thickness of 0.05 inch may beoperated on to produce a flattened tube of the cross-section shown inFig. 21 about 0.75 inch wide outside and 0.09 inch thick outside.

By practice of the present invention it is unnecessary preliminarily tostraighten the tube of circular cross-section, being operated on, whilethe flattened tube, produced in a single pass through the apparatus, isuniformly straight and of uniform cross-section. Further, the onlylimitation on the length of the tube that may be produced is determinedby the length of the tube constituting the starting material. Stillfurther, the tubes can be produced vary rapidly, say at the rate ofabout feet per minute, as compared to the rate at which they may beproduced by drawing operations.

In the embodiment of apparatus shown by the drawings a table I (Figs. 1and 2) is provided of sufficient length to support the tubes 3 to beoperated on, which tubes before being operated on are, as shown, ofcircular cross-section. Adjacent the table is a support 5 carrying aguide I for the tubes. As shown (Figs. 1, 2 and 12), this guidecomprises an elongated member having a slot 8 so formed as to providewalls 9 adapted to engage with the exterior lateral walls of the tube,the top of the slot being open so that the operator may readily placethe ends of tubes in the slot and push them toward the first of theseries of cooperating rolls hereinafter mentioned. Conveniently, theguide 1 is detachably secured to the support 5 as by removable studbolts 'll so that 12 to the oval cross-section illustrated in Fig, 16.;

As best illustrated in Figs. 13, 14, 15'and16, the peripheral lengths ofthe openings formed-by the pairs of cooperating grooves .transverse tothe tube are greater than the circumference' of;

the tube, so that the extreme edge portions of the grooves do notoperate on the extreme edge portions of the tube. Were these peripherallengths of the grooves less-than the circumference of the tube the wallsof the oval tube would be locally crumpled, On the other hand, were suchlengths substantially the same as the circumference of the tube, thewalls of the oval tube at one side of its major medial plane would beliable to be offset from its walls at the opposite side of that planebecause of the practical impossibility of insuring that the groove inone roll will be exactly in registry with the groove in its cooperatingroll. The existence of local crumpling of the tube wall or of offsets init may result in splitting or weakening of that wall when the tube isoperated on further to flatten it, and in any event will causeobjectionable malformation of the tube.

7 Asa result of the above operation, the bends at opposite edge portionsof the oval tube formed by the rolls I3, l5, l1, I9 are such that thoseedges are rather pointed, these bends being sharper than is suitable forproducing the bends desired at the edges of the finished tube when theoval tube leaving the rolls I9 is subjected to the tube flatteningoperations hereinafter described, the overall efiect of the rolls [3,I5, I! and l9-in this respect being analogous to that which would besecured at the edge portions. of an oval tube if formed by passing atube of circular cross-section between a single pair of cooperating"fiat rolls, which latter, like the rolls illustrated, also would notoperate on the extreme edge portions of the oval tube.

Were the flattening operation continued by passing the tube leaving therolls [9 between flat rolls, or rolls having grooves of the desiredshape of the finished tube, that desired shape would not be secured, theopposite edge portions of the flattened tube in such case beingoverfiattened in the sense that such edges would make a sharper bendthan desired, and it has been found that this would be true even if aseries of pairs of rolls were provided gradually to flatten the tubeleaving the rolls [9. 'To avoid this defect the machine shown isprovided adjacent the driven rolls"!!! with a pair of cooperating idlerolls 23 positioned transverse to'the rolls l9. These rolls 23 areprovided with peripheral grooves 25 which operate on the opposite edgeportions of thefiattened tube to remove the above mentioned sharpness ofthe bends at those edges, so as to increase the radii of curvature ofthose bends to such extent that operating on the tube in the mannerhereinafter described will result in a flattened tube having edgeportions of the desired curvature. It will be observed from a comparisonof Figs. 16 and 17 thatthe. edgerolls 23 secure this result bybendingthe tube walls at the opposite edges of the oval to spread apartthe opposite flattened walls of the tube between those edges, theresulting curvatures at such edges being greater than those of the finalfinished tube. From one aspect the operation performed by the edge rolls23.may be said to be that of blunting the edges of the oval tube leavingthe grooved rolls I9.

- After the tube leaves the edge rolls I! it, according to the presentinvention, is operated on adjacent the center portions of its flattenedsides further to decrease its thickness and further flatten those sides.In this way a minimum of bending oi isuch nature as will act to pointthe opposite edges of thetube will occur, so that in the final tube theedges thereof will be bent approximatelyon arcs of circles and the sidesof the tube will" be substantially flat across their full widths to thetube edges.

To the above ends, in the machine shown the tube after leaving the edgerolls '23 passes between the cooperating driven flat rolls 3|, thenbetween the pairs of cooperating crowned idle rolls 35 and 37 theprofiles of which, as viewed in Figs. 3 and 5, are shown as arcs ofcircles, and finally between the cooperating driven flat rolls 45 Therolls 3!, 35 and 31. are adapted to contact with the center portions ofthe opposite sides or faces of the tube presented to them and actgradually to fiattenthose sides and to decrease the tube thickness,while the rolls act to size'the tube and remove any irregularitiesinitsfiattened sides. Best results will be secured by having the rolls3'! at their crowns spaced apart but slightly more than the rolls 45 soas to cause no'more working of the tube by the latter than isnecessaryto size the tube and cause proper operation of the tubestraightening means hereinafter described.

The spacing between the rolls 45 ordinarily should be very slightly lessthan the desired thickness of the finished tube to compensate for springin such tube, customarily, however, such spring will not amount .to muchmore than about 0.01 inch. By reason of the rolls 3|, 35 and 31 actingat the center portions of .the sides of the tube presented to themexcessive bending at the edge portions of the tube is avoided as aboveexplained, the shape imparted to the edge portions by the edge rolls 23being such as to cause such bending as occurs at the edge portions afterthe tube leaves the edge rolls to result in the edge portions of thefinishedtube being approximately arcs of circles after the tube isoperated on by the rolls 45, .which latter cause the plane flattenedside surfaces of the "tube to extend to the edges defined by these arcs.

Further, pressing the sides of the oval tube toward each other by actingon them adjacent the minor axis of the oval tends to bow outwardlyportions of the tube walls'between that axis and the tube edges, and toavoid such bowing of the walls, and thus make them approximatelyfiat,the arcs defining theprofiles of the crowned rolls are made rather flatso' as to minimize such bowing, it being observed'that an excesstendency of the. walls to bow outwardly will be obstructed by thesurfaces of the crowned rolls opposite where the bowing tends to occur.The radii of curvature of these arcs of the surfaces of the crownedrolls is not critical however so long as it is sufficient to preventmaterial bowing of the walls constituting the sides of the tube.beyondthe limit ofthe spring of those walls, thus to cause the sides'of' the tube to be approximately fiat, because the sizing rolls 45 willremove any slight irregularities in the sides of the tube presented toit. In Figs. 19 and 20 these arcs, for convenience of illustration, areshown of smaller radius than commonly would be used in practice. Inpractice in making a tube of the dimensions mentioned arcs of about 5inches radius will give satisfactory results.

It will be understood that in making a tube of the shape shown in Fig.22, although each of the rolls I3, I5, IT and I9 is shown as grooved,the final rolls IQ of this group of rolls may be flat rolls, and in someinstances even the intermediate rolls I5. Also in many instances fourpairs of rolls need not be employed in this group, but a lesser number,and in some instances it may be necessary to employ a greater number ofrolls. Likewise in some instances the flat pair of rolls 3| may beomitted, and in some instances but one pair of crowned rolls need beemployed. These considerations will depend upon the wall thickness ofthe tube being operated on and the temper of such wall.

It will also be understood, that because of the spring in the tubewalls, the cross-section of the tube after leaving a given pair of rollscommonly will not be exactly the same as when it is between those rolls.For example, the walls of the tube after the latter leaves the rolls 3icommonly will spread apart at its minor axis so that the sides of thetube will not be fiat as shown in Fig. 18. This effect is particularlynoticeable as the tube passes toward the final rolls, because as itpasses through the machine it becomes progressively work hardened andits spring increases. However, as above mentioned, this spring willseldom amount to but more than 0.1 inch measured transversely of thetube. Because of the spring in the tube varying with the wall thickness,shape, size and material of the tube, in practice, if it is necessaryfrequently to make tubes having varying characteristics in theserespects, the various pairs of rolls may be conveniently mounted foradjustment of their axes toward and away from each other in any ofsuitable well known ways. commonly employed for that purpose in rollingmills so that the spacing of the rolls may be readily adjusted by trialto suit the characteristics of any particular tube being produced.

Leaving the rolls 45 the tube passes through the guide indicated in itsentirety at 41 (Figs. 4, 9 and and then onto the top of the table 49(Fig. 3) being guided over the latter by the guide strips 5 I.

The guide 41, as best shown in Figs. 9 and 10, comprises a pair ofspaced upstanding rigid members 53 carried by a plate 55, which plate issecured to a fixed bracket 51 by studs 59 passing through a slot 6| inthe plate so that the members 53 may be adjusted properly to positionthem relative to the path of the tube 3, and so that diflerent plates 55and members 53 may be substituted to accommodate difierent sizes oftubes, the bracket 51 being carried by the support 5. The guide members53 are positioned adjacent the bite of the driven rolls 45 at the exitside thereof. Any tendency of the tube to deviate edgewise from astraight line will cause one or the other of the two edges, dependingupon in which direction the deviation tends to occur, to bear againstone or the other of the guide members and hold the tube against suchdeviation while the rolls 45 are working it, As a result of this thetube passes from between the guide members 53 perfectly straight in sofar as edgewise out of straightness is concerned. Conveniently, toinsure retention Of the tube between the guide members, the same arepreferably bridged by a plate 58.

The guide strips 5|, which are removably secured to the table 49 so thatguide strips may be employed spaced the proper distance apart toaccommodate the width of the tube, restrain the tube from passing overthe table 49 otherwise than in a straight line, and thus act to insurethat the tube in passing over the table will not be accidentally bent.

The pairs of rolls I3 to I9 which work the tube to deform it from itscircular cross-section to an oval cross-section act to level the tube,that is to say, remove any unstraightness that may exist in the tubeoriginally presented to the apparatus. The rolls which subsequently actupon the tube maintain this straightness in so far as fiatwise out ofstraightness of the tube is concerned, while the guide 41, as aboveexplained, insures that the finished tube will be straight ,edgewise.

It will be observed that the several driven rolls progressively act upontube portions of progressively decreasing thickness. Consequently, theserolls tend to place the tube under slight lengthwise tension, and thusavoid buckling the tube. The rolls however do not elongate the tube, thefinished tube being substantially the same length as the tube presentedto the apparatus. Any difference in the speed at which the severaldriven rolls tend to move the tube is compensated forloy.

slippage between the tube and the rolls. Preferably the driven rolls areof the same diameter and rotate at the same speed, or are otherwise ofsuch diameters and rotate at such speeds as will cause the portions ofthe tube between adjacent pairs of rolls to be under slight tension.

The various rolls may be supported and driven in any suitable way. Asshown (see Figs. 1, 3 and 7), the support 5 is provided with bosses 63in which are rotatably supported shafts 55, the latter having taperedends 61 on which the rolls are removably mounted by means of the nuts 59and washers I I, so that different rolls may be substituted toaccommodate tubes of different dimen sions. Opposite the rolls theprojecting ends I3 of the shafts in any suitable way rigidly carrymeshing gears I5 for driving cooperating rolls of pairs of rolls at thesame speed in opposite directions. Also carried by the support 5 areidle gears Ii which mesh with adjacent gears I5. This arrangement ofgearing will be clear from the diagram shown by Fig. 11. The train ofgearing may be driven in any suitable way. As shown, in place of an idlegear between the gears 75 for driving the pairs of rolls 3| and 45 is adriven gear I9 connected to any suitable source of power. As shown(Figs. 3, 4 and 5), this gear is fixedly mounted on a driven shaft SIrotatably supported in the boss 83 carried by the support 5.

As shown (Figs. 3, 4 and 8) the idle rolls 23 are rotatably supported onstuds 85 carried by a bracket 81 secured to the support 5, these rollsbeing removably mounted on the studs, and the bracket being removablymounted on the support, in any convenient way so that rolls of differentdiameter and with different grooves 25 may be readily substituted toaccommodate different sizes and shapes of tubes to be formed.

The crowned rolls 35 and 31, as best shown in Figs. 3, 4 and 5, may beremovably mounted on studs. 89 carried by the "support its!) thatcrowned i,

rollsof different diameter and shape may,- be subs: stituted. -\toaccommodate diiferentrsizes: .and

shapesof tubes.

It willbe understood that, instead oi presenting a tube of circularcross-section to the apparatus,

there may be presented a tube of any cross-sec.- tion intermediate thatshown by Figs; 12 to 21 inclusivain which case .onlythe rolls necessaryto reduce atube of that cross-section to the final cross-section will.be employed'.- Foriexample, a

tube of cross-section shown by Fig.- 16 could be produced in anysuitable way and be presented; to

the machine, in which case the rolls'indicated in Figs; 13, la and wouldbe omitted, while aguide 7 having a slot 8 of proper-shape toaccommodate the tubecould be substituted for the guide. shown.

Similarly it will be understood that the flattened tube produced by themachine need not have the cross-section shown by Fig; 21. It could, forex ample, have the cross-section shown-byFig. 23, in which case, afterthe tube is brought to the,

shape shown in Fig. 19 to space apart thetube face portions at the minorlongitudinal medial plane: 1.

1. Apparatus for forming flattened tubes having continuously spacedwalls circumferentially thereof from tubes of circular cross-section ofthe same wall thicknesses comprising rolling means for flattening a tubeof circular cross-section to one of continuously open oval cross-sectionby operation on opposite faces-of the tube without substantiallyoperating on the edge portions of the tube adjacent the major axis ofthe oval, rolling means for operating on said edge portions of the openoval tube thus formed adapted to increase their radii of curvature andspread apart the faces of said tube while maintaining a tube ofcontinuously open oval cross-section, and rolling means for operating onsaid spaced apart faces adjacent the minor axis of the oval adapted toflatten said faces and decrease the radii of curvature of said edgeportions without operating on the portions of said faces adjacent saidedge portions.

2. Apparatus according to claim 1 comprising a pair of opposed rollsbetween which the tube passes for sizing it after operation thereon ofthe last mentioned means of claim 1, guide means being provided adjacentthe bite of said rolls at the exit side thereof against which one or theother of the opposite tube edges is adapted to bear upon the portion ofthe tube leaving said rolls tending to deviate edgewise from a straightline whereby to produce a tube which edgewise is straight.

3. Apparatus for forming from relatively thin walled tubes of circularcross-section flattened tubes havin exteriorly convex edges comprising aseries of pairs of opposed complementary rolls, the rolls of at leastone pair of which are formed with complementary grooves, forprogressively flattening a tube of circular cross-secti0n to one of ovalcross-section with-out substantially oper: ating on theedge portions. ofthe tube adjacent the majoraxis-of the oval, means engaging thesides'iof the .tube of circular cross-section transverse'rto the axis'ofsaid rolls for. guiding said tube I to thegrooves; of said rolls,,meanscomprisinga pair of rolls positionedtransverse to the first mentioned:rolls adjacent the last of said seriesat the exit side thereof: foroperatin on the edgeportions of the'oval tube thus formed forincreasingthe radii of curvature of said edge per-- tions: andspreading apart thefaces of said' oval tube, means comprising a pair'of opposed crownedrolls forjoperatingon said spread apart faces ad-u jacent the minoraxis. of the oval for flattening saidfaces. anddecreasing the radii ofcurvature of saidedgeportions, means comprising a pair, ofcomplementary. rolls for sizing the tube after beingoperated on by saidcrowned rolls, and op-' erativelyrigid guide means adjacent the biteofsaid rolls for sizing the tube at the exitside thereof opposed to eachedge of the tube adapted to prevent edgewise bending of the portions ofthe tubevleaving said rolls.

4. Apparatus for forming flattened tubes having rounded edges andcontinuously spacedwalls circumferentially thereof from tubes ofopenoval'v cross-section of the same wall thicknesses comprisingopposite cooperating crowned oval tubewith' the minoraxial line of the.oval in the medial plane of the crowns of suchrolls, and,

allowing for the spring of sai faces, ,withsaid crowns spaced apart atsaid plane a dlstanceinot less than the distance between the faces ofthe flattened tube at its edges, whereby to apply. i

rollsadapted-to operateonthe opposite faces-of the.

5. Apparatus accordingto claimA comprisinga pair of cooperating exitrolls for operating on the faces of the tube for. sizing the tubeafterbe-' a ing operated "on by said'crowned rolls,.:guide: :means beingprovided adjacentathe bite'of saidr exit rolls against which one or theother of the opposite tube edges is adapted'to bear upon the'portion ofthe .tube leaving said .exit rolls' tending to deviate from a. straightline wherebyjto produce a tube which edgewise is straight;

6. The method of forming a, flattened tubeu,

havingv continuously spaced walls circumferentially thereof from a tubeof circular.cross-secs"v tion of the same wall; thicknesses which .com-

prises flattening a tubev of circular cross-section to one ofcontinuously open oval cross-section by. pressing the .tube of circular:cross-section fromopposite sides thereof. without 'substantiallyiops 4eratingon the portions of the oval adjacentits major axis, pressing theopen oval- .tubethus formed from its oppositeedges. to increase theradii of curvature of its edge portions, and subsequently pressing thetube from its opposite faces adjacent the minor axis of the oval tofiat-- ten said faces anddecrease saidradii of curvaturewithoutoperating on the portions of said facesradjacent said edge.portions.

'7. The method oi forming a flattened tubezhave ing continuously spacedwallsrcircumferentiallyz thereof from a' tube 'of circular.cross-sectionof the same-wall thicknesses which comprises flat-.

tening a: tube of circular cross-section to one of continuously openoval. cross-section by rolling:. the .tubeof circularqcrossesection topress its op-.: posite sides: toward each:other;:without substan;

tially operating on the portions of the tube adjacent the major aXis ofthe oval, rolling the open oval tube thus formed edgewise to increasethe radii of curvature of its edge portions and to spread apart itsfaces, and subsequently operating on the tube by passing it betweencooperating rolls engaging said faces adjacent the minor aXis of theoval for decreasing said radii and flattening said spread apart faceswithout operating on the portions of said faces adjacent said edgeportions.

8. The method of forming a flattened tube having continuously spacedwalls circumferentially thereof from a tube of circular cross-section ofthe same wall thicknesses which comprises flattening a tube of circularcross-section to one of continuously open oval cross-section by rollingthe tube of circular cross-section to press its opposite sides towardeach other without substantially operating on the portions of the tubeadjacent the major axis of the oval, rolling the open oval tube thusformed edgewise to increase the radii of curvature of its edge portionsand to spread apart its faces, and subsequently operating on the tube bypassing it between cooperating crowned rolls engaging said facesadjacent the minor axis of the oval for decreasing said radii andflattening said spread apart faces without operating on the portions ofsaid faces adjacent said edge portions.

9. The method of forming a flattened tube having rounded edges andcontinuously spaced walls circumferentially thereof from a tube of openoval cross-section of the same wall thicknesses which comprises pressingthe oval tube from its opposite faces by forces applied thereto confinedto the portions thereof adjacent the minor axis of the oval to flattensaid faces and decrease the radii of curvature of its opposite edgeportions without operatin on the portions of said faces adjacent saidedge portions, and, allowing for the spring of said faces, withoutpressing said portions thereof to which said forces are applied towardeach other a distance less than the distance the portions of said facesadjacent said edge portions are deformed toward each other.

10. Apparatus for forming flattened tubes having rounded edges andcontinuously spaced walls circumferentially thereof from tubes of openoval cross-section of the same wall thicknesses comprising means adaptedto operate on the faces of the oval tube adjacent the minor axis of theoval for decreasing the radii of curvature of the edge portions of theoval, and means providing abutment surfaces opposed to portions of saidfaces which are between said axis and the tube edges acting to preventexcess outward bowing of said portions.

11. The method of forming a flattened tube from a tube of open ovalcross-section of the same wall thicknesses which comprises pressing theoval tube from its opposite faces by forces applied thereto confined tothe portions thereof adjacent the minor axis of the oval to decrease theradii of curvature of its opposite edge portions, and during thepressing operation providing abutment surfaces opposed to portions ofsaid faces which are between said axis and the tube edges for preventingoutward bowing of said portions beyond the limit of spring of the tubewalls.

LOUIS G. GLESMANN.

REFERENCES GITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,442,850.June 8, 1948.

LOUIS G. GLESMANN It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionas follows: Column 8, line 3, claim 3, for axis read axes; and that thesaid Letters Patent should be read With this correction therein that thesame may conform to the record of the case in the Patent Office.

Signed and sealed this 10th day of August, A. D. 1948.

THOMAS F. MURPHY,

% Assistant Gammz'ssz'oner of Patents.

